Keywords

Adhesion: The property of molecules binding to other molecules of a different substance.

Alpha helix: A protein secondary structure - coiling of a polypeptide chain to form a right-handed spiral held in place by hydrogen bonds.

Amino acids: Monomer of polypeptides.

Amphoteric: A molecule that can act as an acid or a base.

Benedict’s test: A biochemical test for the presence of reducing sugars.

Beta pleated sheet: A folded protein secondary structure held in place by hydrogen bonds.

Biuret’s test: A biochemical test for the presence of proteins.

Carbohydrates: Family of molecules that includes starch, glycogen, cellulose and glucose - often used as an energy source, energy store or in the formation of glycoproteins.

Cohesion: The property of molecules binding to other molecules of the same type.

Condensation reaction: A type of chemical reaction in which two molecules are joined together by a covalent bond to form a larger molecule, releasing a molecule of water.

Denaturation: An irreversible change in the tertiary structure of a protein molecule. It leads to loss of function in most proteins.

Disaccharide: A molecule consisting of two monosaccharide sugars joined by a glycosidic bond.

Disulfide linkage: A covalent bond formed between the sulfur atoms in two cysteine amino acid residues.

Ester bond: A bond formed in a condensation reaction between the -OH group of a carboxylic acid and an -OH group of an alcohol.

Fibrous protein: A protein with a relatively long, thin structure, which is insoluble in water and metabolically inactive, often having a structural role within the organism.

Globular protein: A protein with a relatively spherical structure, which is soluble in water and often having metabolic roles within the organism.

Glycosidic bond: Covalent bond formed when monosaccharides are joined together in condensation reaction.

Hydrogen bond: A weak electrostatic attraction between the partially positively charged and partially negatively charged atoms in polar molecules.

Hydrolysis reaction: A reaction in which a large molecule is broken down into two smaller molecules, by the addition of water and the breaking of a covalent bond.

Ionic bond: Electrostatic attraction between oppositely charged ions.

Latent heat of vapourisation: The amount of heat required to enable a molecule to separate from other molecules around it - turning a liquid into a vapour.

Monomers: Small molecules of the same general type that are joined in condensation reactions to form a polymer.

Monosaccharides: Monomer of polysaccharides.

Non-reducing sugar: Disaccharides (e.g. sucrose) that do not reduce other molecules.

Peptide bond: The covalent bond formed when amino acids are joined together in condensation reactions.

Polar molecule: Hydrophilic molecule with an unequal distribution of charge.

Polymer: A large molecule made by covalently joining many similar small molecules together in a condensation reaction.

Polypeptide: A polymer consisting of many amino acid monomers covalently bonded together by peptide bonds.

Polysaccharide: Polymer formed from many repeated condensation reactions joining many monosaccharide monomers together.

Primary structure: The sequence of amino acids found in a polypeptide held together by peptide bonds.

Prosthetic group: A non-protein group covalently attached to a polypeptide.

Protein: A large molecule composed of one or more polypeptide chains.

Qualitative test: A test that reveals the presence or absence of a substance but not its numerical quantity.

Quantitative test: A test that gives readings and recordings that are numerical.

Quaternary structure: Level of protein structure where a protein consists of more than one polypeptide chain.

Reducing sugars: Sugar molecules including all monosaccharides and some disaccharides that can reduce other molecules.

Saturated fatty acid: Only contains single C-C covalent bonds.

Secondary structure: The regular coiling or folding parts of a polypeptide chain due to the formation of hydrogen bonds between the C=O and NH groups in the polypeptide backbone. Includes alpha helix and beta pleated sheet.

Specific heat capacity: The amount of energy required to make substance change temperature.

Steroids: A class of non-polar lipid molecules e.g. cholesterol, testosterone.

Tertiary structure: The overall 3D shape of a polypeptide formed as a result of interactions between the amino acid side chains (R groups).

Triglyceride: Most common lipid in the body, containing three fatty acids and a glycerol molecule. They are entirely hydrophobic and form large droplets inside cells.

Unsaturated fatty acid: Contains one or more C=C double bond.